Array-type image forming apparatus and method to compensate image density

Abstract

An array-type image forming apparatus and a method for compensating an image using the same include an image density determination unit to determine the image density of each line on a page, a storage unit stores one or more threshold values and a control unit compensates the image density by comparing the determined image density of each line and the threshold value. When the image density reaches the threshold value, the control unit modifies the amount of heat supplied to a print head, thus modifying the amount of ink applied to subsequent lines on the page, in order to provide compensation for the image density.

1. An array-type image forming apparatus, comprising:
 an image density determination unit to determine the image density of each line on a page; 
 a storage unit to store one or more threshold values to determine whether to compensate image density on the page; and 
 a control unit to determine whether to compensate the image density by comparing the determined image density of each line and the threshold value, and compensating the image density on the page according to the comparison result, 
 wherein the storage unit stores a reference value based on which the image density of each line is determined to be high or low, a first threshold value which is the allowable number of lines, having a high image density, and a second threshold value which is the allowable number of lines having a low image density. 
 
     
     
       2. The apparatus of  claim 1 , wherein the control unit counts the number of lines having an image density higher than the reference value, and compensates the image density if the counted number of lines reaches the first threshold value. 
     
     
       3. The apparatus of  claim 2 , wherein the control unit compensates the image density if there are lines having a high image density which are repeated successively until the first threshold value is counted, or if the number of lines having a high image density in a certain area reaches the first threshold value. 
     
     
       4. The apparatus of  claim 2 , wherein the control unit resets the counted number of lines if one page has been printed completely. 
     
     
       5. The apparatus of  claim 1 , wherein the control unit counts the number of lines having an image density lower than the reference value, and compensates the image density if the counted number of lines reaches the second threshold value. 
     
     
       6. The apparatus of  claim 5 , wherein the control unit compensates the image density if there are lines having a low image density which are repeated successively until the second threshold value is reached, or if the number of lines having a low image density in a certain area reaches the second threshold value. 
     
     
       7. The apparatus of  claim 1 , wherein the control unit compensates the image density by changing a fire strobe pulse. 
     
     
       8. The apparatus of  claim 1 , further comprising an output unit to notify a user that the image has been compensated by displaying or printing a message. 
     
     
       9. The array-type image forming apparatus of  claim 1 , wherein the array-type image forming apparatus ejects ink to form an image on the page, and
 the control unit compensates the image density on the page by adjusting a size of ink droplets onto the page. 
 
     
     
       10. A method to compensate an image using an array-type image forming apparatus, the method comprising:
 determining the image density of each line on a page; 
 comparing the determined image density of each line with at least one threshold value to determine whether to compensate image density on the page; and 
 compensating the image density on the page according to the comparison result, 
 wherein in the compensating operation, the number of lines having an image density higher than the reference value is counted, and the image is compensated if the counted number of lines reaches a first threshold value, and 
 wherein the first threshold value is the allowable number of lines having a high image density. 
 
     
     
       11. The method of  claim 10 , wherein in the compensating operation, the image is compensated if there are lines having a high image density which are repeated successively until the first threshold value is reached, or if the number of lines having a high image density in a certain area reaches the first threshold value. 
     
     
       12. The method of  claim 10 , wherein in the compensating operation, the number of lines having an image density lower than the reference value is counted, and the image is compensated if the counted number of lines reaches a second threshold value,
 wherein the second threshold value is the allowable number of lines having a low image density. 
 
     
     
       13. The method of  claim 12 , wherein in the compensating operation, the image is compensated if there are lines having a low image density which are repeated successively until the second threshold value is reached, or if the number of lines having the low image density in a certain area reaches the second threshold value. 
     
     
       14. The method of  claim 10 , further comprising resetting the counted number of lines if one page has been printed completely. 
     
     
       15. The method of  claim 10 , wherein in the compensating operation, the image has been compensated by changing a fire strobe pulse. 
     
     
       16. The method of  claim 10 , further comprising notifying a user that the image is compensated, by displaying or printing a message. 
     
     
       17. The method of  claim 10 , wherein compensating the image density includes adjusting an ink dot size of ink dots that form the image. 
     
     
       18. A method of determining whether to compensate an image using an array-type image forming apparatus, the method comprising:
 determining the image density of each line on a page; 
 determining whether to compensate image density by comparing the determined image density of each line with at least one threshold value; and 
 compensating the image density on the page according to the comparison result, 
 wherein in the compensating operation, the number of lines having an image density higher than the reference value is counted, and the image is compensated if the counted number of lines reaches a first threshold value, and 
 wherein the first threshold value is the allowable number of lines having a high image density. 
 
     
     
       19. The method of  claim 18 , further comprising:
 compensating the image density based on the comparison. 
 
     
     
       20. The method of  claim 18 , wherein determining the image density of each line includes counting one or more dots, to arrive at a number of the total dots counted for each line. 
     
     
       21. The method of  claim 20 , wherein determining the image density of each line further includes comparing the total dots counted for each line to a reference value. 
     
     
       22. The method of  claim 21 , wherein determining whether to compensate image density includes counting a number of lines such that the total dots counted for each line is greater than the reference value. 
     
     
       23. The method of  claim 21 , wherein determining whether to compensate image density includes counting a number of lines such that the total dots counted for each line is less than the reference value. 
     
     
       24. An array-type image forming apparatus, comprising:
 an image density determination unit to determine the image density of each line on a page; 
 a storage unit to store one or more threshold values to determine whether to compensate image density of ink droplets on the page; and 
 a control unit to determine whether to compensate the image density by comparing the determined image density of each line and the threshold value, 
 wherein the storage unit stores a reference value based on which the image density of each line is determined to be high or low, a first threshold value which is the allowable number of lines having a high image density, and a second threshold value which is the allowable number of lines having a low image density. 
 
     
     
       25. A method to compensate an image using an array-type image forming apparatus, the method comprising:
 determining the image density of each line on a page; and 
 compensating the image density by comparing the determined image density of each line with at least one threshold value to determine whether to compensate image density at each line, 
 wherein in the compensating operation, the number of lines having an image density higher than the reference value is counted, and the image density is compensated if the counted number of lines reaches a first threshold value, and 
 wherein the first threshold value is the allowable number of lines having a high image density.